Amanda Ripanykhazov wrote:
On Feb 19, 4:18 pm, Archon wrote:
Amanda Ripanykhazov wrote:
I am hoping this question isnt too basic for this forum but I am
trying to replace some rechargeable batteries (in a Roomba: I
understand that generally only one or two start malfunctioning over
time and that it is usually the same one). It MUST be easier than I am
finding it.
I can just about solder on a connection but these rechargeable C cells
(nickel metal hydride? I am pretty sure they aren't lithium!) always
seem to have some sort of electro-welded rectangular plate connecting
the batteries which wont come off with a normal soldering gun? Or do
I just have to apply an inordinate amount of heat at exactly the
position where the ;nick' seems to be in the plate? Given the amount
of heat I seem to have applied to it already with no effect
whatsoever, to me it seems that this might damage the cell?
Is there some trick to doing this please or am i supposed to use a
dremel wheel to cut the plates off, leaving just the electro-weld to
which I solder the wire for the new cell?
Hi Amanda, You might want to look at this link, it details what to expect.

http://www.robotreviews.com/hack2/battery.shtml

Theres a good link to thread of advice on which cells to buy etc

Good luck, I'm about to try the same on my Roomba, JC

Hi JC

Yes, I had seen that and have two batteries to do: So my problem is
probably in getting enough good cells in one of them if I can figure
out how (as Mike would put it) to join up two separate tabbed cells
without having a spot welder

It is noteworthy that the on line 'experience based' instructions say
that you can solder where there was spot welding beforehand. (They
dont tell how to get the tabs off in the instructions which I saw,
which is why I posted here)

Amanda Ripanykhazova

Hi Amanda, I haven't checked out the construction of the Roomba battery
as yet but I'm guessing your problem is the original links between the
batteries is not an easily solderable metal, maybe stainless steel?. In
the link I gave you they are replacing all the batteries so soldering to
the original batteries was not a required. The metal case of the
batteries can usually be soldered to but its not recommended as others
have stated. You may need a special flux and a high wattage iron to make
decent connection to the original welded tags. JC